GAP Titan DX - Test Details

GAP Titan DX - 10 Meter Test

Configuration:

The GAP Titan DX and the reference antenna were placed at an elevation of 5 feet over homogeneous ground 103 feet apart (appx. 3 wavelengths). Feedline lengths were adjusted to detune each antenna when inactive. Mutual coupling was evaluated through EZNEC simulation, and the perturbation in the patterns was found to be less than +/- 1 dB, with no particular azimuth direction being favored. Both antennas were fed with nearly equal lengths of RG8/U foam feedline.

The reference antenna (designated 10VT11.ez) is a monoband vertical, 10.9 feet high, with 2 elevated radials 5.3 feet long. Simulations using EZNEC indicate that the reference antenna has a maximum gain of 4.89 dBi, at a launch angle of 10 degrees. The radiation plot is shown below.

10 Meter Test Details:

All tests were performed from May 2 through May 10, 1999.
Solar Flux Range: 126 - 172
Number of signals recorded: 43
Number of testing Sessions: 8

Average difference per call: -11.0 dB

There were moderate differences between sessions, and a general trend for the Titan DX to perform more poorly on longer distance (DX) paths.

GAP Titan DX - 15 Meter Test

Configuration:

The GAP Titan DX and the reference antenna were placed at an elevation of 5 feet over homogeneous ground 80 feet apart (slightly under 2 wavelengths). Mutual coupling was evaluated through EZNEC simulation, and the perturbation in the patterns was found to be on the order of +/- 1 dB, with no particular azimuth direction being favored. Both antennas were fed with equal lengths of RG8/U foam feedline. Due to it's high SWR on 15 meters, the Titan has an additional 0.7 dB of calculated feedline loss.

The reference antenna (designated 15VT11.ez) is a monoband vertical, 13.7 feet high, with 2 elevated radials 7.8 feet long. Simulations using EZNEC indicate that the reference antenna has a maximum gain of 4.68 dBi, at a launch angle of 10 degrees. The radiation plot is shown below.

15 Meter Test Details:

Gain of GAP Tital DX compared to monoband reference antenna:
Average Range of Session # Calls Difference (dB) Difference (dB) 1 21 -14.8 -20, -13 2 14 - 2.9 -5, -2 3 6 - 3.0 -4, -2 4 3 -11.0 -15, -8 5 9 - 9.8 -15, -5 6 3 - 7.0 -8, -5 7 10 - 6.1 -8, -3 8 6 - 5.2 -8, -3 9 4 - 3.3 -5, 0 10 9 - 5.7 -8, -4

Test Summary:

All tests were performed from April 2 through April 11, 1999.
Solar Flux Range: 100 - 144
Number of signals recorded: 85
Number of testing Sessions: 10

Average difference per call: -7.8 dB
Average difference per session: -6.9 dB

Transmission Line Losses:

Note the additional 0.7 dB of transmission line loss for the GAP Titan due to its higher SWR. At first I was inclined to factor this out of the gain differentials, but upon further consideration I decided that the Titan's greater loss was unavoidable to a large extent since it can not be tuned for each band. At least there is no mention of any possible tuning in the GAP manual. However, it is important to note that the loss will vary depending on the transmission line type and length.

Gain Disparity: Sessions vs. Overall

One very surprising observation was that the gain differences during any given session were quite homogeneous compared to the gain difference between sessions. I speculate that perhaps changing band conditions between sessions caused the angle of the received signals to vary significantly, and that the Titan may have a significantly different pattern, perhaps with secondary lobes. I hope that some of those more knowledgeable than me will offer further insight.

On a side note, this disparity between sessions makes me question other published performance tests that are based upon a single testing session.

GAP Titan DX - 20 Meter Test

Configuration:

The GAP Titan DX and the reference antenna were placed at an elevation of 5 feet over homogeneous ground 103 feet apart (appx. 1.5 wavelengths). Feedline lengths were adjusted to detune each antenna when inactive. Mutual coupling was evaluated through EZNEC simulation, and the perturbation in the patterns was found to be on the order of +/- 1 dB, with no particular azimuth direction being favored.

Both antennas were fed with nearly equal lengths of RG8/U foam feedline. Due to it's higher SWR, the monoband reference antenna has an additional 0.1 dB of calculated feedline loss.

The reference antenna (designated 20VT11.ez) is a monoband vertical, 20.0 feet high, with 2 elevated radials 12.5 feet long. Simulations using EZNEC indicate that the reference antenna has a maximum gain of 4.54 dBi, at a launch angle of 11 degrees. The radiation plot is shown below.

20 Meter Test Details:

Gain of GAP Tital DX compared to monoband reference antenna:
Average Range of Session # Calls Difference (dB) Difference (dB) 1 2 +1.50 -2, +5 2 15 +0.13 -5, +5 3 7 +0.14 -2, +3 4 23 -0.65 -4, +2 5 13 +0.77 -5, +5

All tests were performed from April 17 through April 18, 1999.
Solar Flux Range: 116 - 123
Number of signals recorded: 60
Number of testing Sessions: 5

Average difference per call: 0.02 dB

Given the margin or error, the difference is effectively zero. In nearly all cases the GAP Titan DX had very similar signal strength compared to the monoband reference antenna. The gain similarities during all sessions were also quite homogeneous, which suggests that the Titan DX has a pattern similar to the monoband reference antenna.

GAP Titan DX - 40 Meter Test

Configuration:

The GAP Titan DX and the reference antenna were placed at an elevation of 5 feet over homogeneous ground 71 feet apart (appx. 0.5 wavelengths). Special care was taken to detune each antenna when inactive. Gain figures were adjusted to reflect differences in feed line loss. Mutual coupling was evaluated through EZNEC simulation, and the perturbation in the patterns was found to be on the order of +/- 1.7 dB, depending on the azimuth direction.

The reference antenna (designated 40VT11.ez) is a monoband vertical, 42.0 feet high, with 2 elevated radials 21.0 feet long. Simulations using EZNEC indicate that the reference antenna has a maximum gain of 4.62 dBi, at a launch angle of 10 degrees. The radiation plot is shown below.

40 Meter Test Summary:

All tests were performed from May 14 through May 17, 1999.
Solar Flux Range: 144 - 144
Number of signals recorded: 55
Number of testing Sessions: 5

Average difference per call: -7.6 dB

Due to effects of mutual coupling, the margin of error could excede +/- 1 dB.
The differences in gain were remarkable homogeneous within and between sessions. No correlation could be discerned for path length (distance between stations). This suggests that the Titan DX has a pattern similar to the monoband reference antenna.

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